Coil form



Jan. 8, 1957 J. F. GORDON 2,777,116

' con. FORM Filed llay 13, 1952 VENTOR. JA F. GORDON ATTORN United States Patent COIL FORM James F. Gordon, Baltimore, Md., assignor to Bendix Aviation Corporation, Towson, Md., a corporation of Delaware Application May 13, 1952, Serial No. 287,541

2 Claims. (Cl. 336-208) This invention relates to the winding of coils of Wire or similar materials upon toroidal forms and more particularly to a coil form for such use.

In electrical and electronic devices it is often advantageous to use coils of wire wound upon toroidal or doughnut-shaped cores. Windings of this type have the advantage of enclosing the magnetic field of the coil and thus reducing unwanted coupling to other portions of the circuit. This is particularly desirable in miniaturized equipment where the circuit components are placed very close to each other.

The winding of wire upon such cores, however, is attended with difiiculties due to the completely enclosed nature of the core and this is particularly true with coils of smaller size. It is also necessary to provide some means of insuring that the turns of the winding retain their uniform spacing.

It is an object of this invention to provide a coil form which facilitates the winding of the coil.

It is another object of the invention to provide a coil form which automatically tensions the wound coil, thus tending to retain the desired spacing of the turns.

It is a further object of the invention to provide a coil form which will accomplish the above results and yet remain simple and inexpesive.

The above and other objects and advantages of the invention are realized by a coil form interrupted by a cut extending diagonally through the toroid.

In the drawing:

Fig. l is a plan view of a coil form embodying the invention; and

Fig. 2 is a similar view of such a form with a coil wound thereon.

Referring now more particularly to the drawing, Fig. 1 shows a toroidal coil form 1 which may be of any resilient non-conductive and non-magnetic material. Examples of materials that can be used are lucite, polystyrene and other resilient dielectric materials. The form is interrupted at 2 by a cut extending completely through the ring at this point. The toroid can be considered as being generated 2,777,116 Patented Jan. 8, 1957 "ice by the rotation of a circle about an axis in its plane and the out should extend diagonally with respect to this generating circle. Near the inner termination of the cut are two holes 3 and 4 extending substantially radially through the ring. The holes 3 and 4 could as well have been near the outer termination of the cut.

Fig. 2 illustrates the completed coil. The coil is formed of a wire 5 and is started by inserting one end 6 of the wire through the hole 3. Winding of the coil then proceeds and is facilitated by the presence of the slot 2. The wire can be passed through the slot in making each turn of the coil. As the coil is completed the last few turns will be wound about the ends of the form at the cut 2 and will bind them together thus closing the opening as indicated in Fig. 2. The remaining end 7 of the Wire is then passed through the hole 4.

The resilient nature of the core material will cause the form to attempt to reopen the slot or cut 2 as in Fig. 1 and this will place the coil under tension, thus tending to retain the turns in their desired location on the form.

While the coil form has been described with respect to the forming of a coil of wire for use in an electrical circuit, it is obvious that a form of this type will otter the same advantages in the winding of any elongated material into a coil of circular shape.

What is claimed is:

1. The combination of a coil form and a coil of elongated material wound thereon, said form having the shape of a toroid and being completely interrupted by a single cut extending obliquely at an angle of at least with respect to the plane of the curve generating said toroid, said form being of material which is electrically nonconductive and non-magnetic and is of such springiness that said cut would normally be open but may be closed by the winding of said coil material about the portion of the form interrupted thereby, said coil being wound around said form including the ends thereof and substantially closing said cut.

2. The combination of claim 1, said form having a pair of holes extending substantially diametrically therethrough, said holes being mutually adjacent and adjacent said cut, and each of said coil material extending through a respective one of said holes.

References Cited in the file of this patent UNITED STATES PATENTS 1,637,649 Kupka Aug. 2, 1927 1,766,048 Trogner June 24, 1930 1,996,823 Osnos Apr. 9, 1935 2,371,756 Gomberg Mar. 20, 1945 2,469,103 Carlson May 3, 1949 

